Electrical resistance.



No. 845,997. PATENTED MAR. 5, 1907. A. O. BENEGKB.

ELEGTRIGAL RESISTANCE. APPLICATION FILED 11mm, 1906.

WITNESSES. IIVVENTOR AWOR/VEYS.

UNITED STATES PATENT OFFICE.

ADELBERT 0. BENEOKE, OF NEWARK, NEW JERSEY, ASSIGNOR TO THE AMERICANINSTRUMENT COMPANY, OF NEWARK, NEW JERSEY, A COR- PORATION OF NEWJERSEY.

ELECTRICAL RESISTANCE.

Specification of Letters Patent.

Patented March 5, 1907.

Application filed June 1,1906- Serial No. 319,697.

To (all whom it may concern:

Be it known that I, ADELBERT 0. BE- NECKE, a resident of Newark, in thecounty of Essex and State of New Jersey, have invented certain new anduseful Improvements in Electrical Resistances, of which the following isa specification My invention relates to improvements in resistanceswhich are intended to carry comparativcly large currents, and especiallyto shunts for electrical measuring instruments.

The object of my invention is to reduce the mechanical size of suchresistances 'to a minimum, which is particularly important in electricalmeasuring instruments, shunts which have to be inserted in theconductors carrying the current to be measured. If such resistances weregiven a sullicient cross section not to become overheated b the amountof electrical ener y consumed in the same by conversion into Iieat, theywould be so enormously large that their use would become prohibitive.

There have been made several attempts in the art to desi n suchresistances in such a manner that the dissipation of the heat generatedin the same is aided by the cooling effect of the air-currents or by th8radiation from large surfaces. The most successful attempt in thisdirection is disclosed in Unite States Patent No. 497,482, granted toEdward Weston, dated May 16, 1893. In the specification of this patentthe inventor states that he has been able to send a current of onethousand amperes through each square inch of cross-section of Germansilver without overheating.

My invention has enabled me to pass a current of ten thousand or eventhirty thousand amperes to each s uare inch cross-section of a similarmateria without overheating the same. I have accomplished this result bymaking the terminal plates of my resistances of a material of hi helectrical conductivity, as copper with amp e cross-section and mass tocarry the current for which the resistance is intended without beingheated to any appreciable amount, and by reducing the cross-section ofthe resistance material inserted between these terminals to such anextent that the necessary lengths to make up a resistance of requiredvalue becomes so small that any heat generated in the same will berapidly conducted away and absorbed by the large and massive terminals.

In carrying out my invention I make use of the structure hereinafterdescribed, and illustrated by the accompanying drawings, in which--Figure 1 is a side view of my improvement. Fig. 2 is a plan view of thesame, and Fig. 3 illustrates a slight modification.

Like letters of reference refer to similar parts throughout thespecification and drawings.

The device consists, essentially, of the massive terminals o and I),made of a material of high electrical coruluctivity, connceted togetherby the resistance material 0 of small cross -section and correspondingshort lengths. In practice lfind it convenient to fix the resistancematerial into the ends of the terminals a and b by slotting the adjacentends of the terminals, as illustrated in Fig. 1, and then inserting theedges of the resistance material into such slots and soldering the sameinto position. However, any convenient method may be employed foruniting the resistance material with the terminals in intimate metalliccontact.

In the selection of suitable resistance material it often happens thatsuch material when heated by the passage of an electrical current in theopen atmosphere will oxidize, and thereby deteriorate. To prevent thisoxidation and keep the resistance material from direct contact with theatmosphere, I find it convenient to serrate or glovetail adjacent endsof the terminals, as illustrated in Fig. 1, and to iill the space su1=rounding the resistance material with some non-conductin fireproofsubstance 71. For

example, pow ered glass held to ether b .some suitable binder, or mica,asbestos, or

any other material will answer the purpose, so long as it will kec theresistance material from contact with tie atmosphere and will form anelectrical insulator. L

As a convenient means of connecting such a resistance into an electricalcircuit provide bolts and nuts (I, by which the ordinary bus-bars may beconnected to the ends of the device.

In case the device is used as a shunt for electrical measuringinstruments I provide employed b main connection'with themassconductivity, and a conductor 0 tenths of an inch. It is evidentthat the unit or standard,when they the furthermore, the binding screws6, to which the electrical measuring instrument 9 1s connected by meansof conductor-wires f.

The resistance material 0 may be in the 3 form of a single thin sheet,as shown in Fig. 1, or in the form of a number of sheets arranged sideby side ,or one on top of the other or m the form of a single wire or anumber of wires, as substantiall illustrated in Fig. 3.

I have foun by experiments that the crosssection of the resistancematerial can be reduced almost indefinitely; but in practice I find thatin order to produce a number of such devices of uniform resistance thelength of the resistance material should best be not reduced to morethan a length of about twoshorter these lengths are chosen the moredifficult it will be to keep the same exactly within desired limits. I

Inoperation when such a resistance is connected' in a circuit thecurrent will pass from the terminal a to the terminal I) through theresistance material 0. A certain amount of electrical energy will beconsumed in the resistance material and converted into heat. This amountis directly proportional to the resistance and to the square of currentpassing through thesame. The heat developed in the resistance materialin case. the density of the current is as large as I have mentionedabove would under ordin circumstances be .sufi'cicnt to fuse theresistance material and therewith to render the device inoperative. Theextreme short 'le he of the resistance material thereby bfingin theterminals into such close'proxi'r'nity, oweveL-as ive termin s preventany overheating of the resistance material, as all'heat'generated in esame is. rapidly conducted-away} by the, terminals whose masses aresufficientjto 'ab sorb the heat without becomi g zhemselves overheated.1 It frequently happens in practicathat it is desirable to have aresistance of; greater can rying capacitythan is found in a structuremade in accordance with Figs. 1 and-2; Un der such conditions it isonly-necessaryto couple up several units of this tgp'e inpa'rallhi in te circuit or,.better still, top ace several of. the same one upon theother and connect".- them all togetherb means of the connecting boltsand nuts d. n this manneri'tispossi-- ble to construct the resistances,after'a single coup ed together, as described, to pro co. therequlred-resistance."

I claim:- V v 31 An electrical rfiistance device, consisting of-twoblocks'of metal of hifgh s ecific s. sp r cific resistance and-shortlength connecting saidblocks of. metal the free length-of sa'i conductorbeing such that the'heat gener- -ing1 of two, blocks ofmetal of hi hspfcific ated therein by the passage of a current there-' through, isconducted to and absorbed b Y said blocks of metal as rapidly as suchheat is enerated, whereby said conductor will nothe overheated.

An electrical resistance device, consisting of a short conductor of highspecific resistance, connecting two masses or blocks of metal of highspecific conductivity, the free length of said conductor being such thatthe heat generated by the passage of an electric current therethrou hwill be absorbed b said blocks of metal as rapidly as generated, wherebysaid conductor will not become overheated.

3. An electrical, resistance device, comprisin two blocks or masses ofmetal of high speci 0 conductivit separated by a short space, aconductor of i h specific resistance connected to said blocEs andspanning said space, the length of said conductor being such that theheat generated by the passage of a current therethrou' h, is conductedto and absorbed by said looks or masses of metal as rapidlyas generated,whereby said conductor wi 1 not become overheated.

4. A resistance device for electric circuit, comprising two blocks ormasses of metal of highs ecific conductivity',.and a conductor of bigspecific resistance connecting said blocks or masses of metal, saidconductor being of such small cross-section. as to produce the desiredresistance within such a short length thereof,-that the heat generatedby the, passage of an electric current there- 'through Wlll be conductedto and absorbed by the said blocks or masses of metal as rapidl asgenerated, whereby said conductorwi 1 not becomeoverheated.

5-, An electrical resistance device, consistconductivity, and aconductor 0 hig spe- ,cific-resistance and short length connectingsatdblocks of metal, the free length of. said eonductor bcing such thatthe heat generated] therein by :the passage of a current therc'through,is conducted to; and absorbed by said-blocks of metal as rapidly asgenerstedvwhereby said conductor will not be overheated; ands fire-proofinsulating materdiatinclosing the free surface of sa d conubtOil 'ing ofafs'hort conductor .of high specific resistanceconnectingtw'o masses orblocks of metal oi'high specific conductivity, the free length of.saidco'nductor being such that the.

.heatgenerated by the passageof an electric current therethro h will beabsorbed b said blocksof'met as rapidl as generate whereby said*conductorwil not be overheated, anda fireproof insulating materialinclosing thefi'eesurface of said conductor.

7. Anelectrical resistance device comprising' two blocks or masses ofmetal oi high spe- '6. 'An eIectrical resistance device, consistsaidresistance device in an electric circuit.

cific conductivit separated by a. short space, a conductor of i hspecific resistance connected to said bloc s and spanning said space,the length of said'conductor being such that the heat generated by thepassage of a current therethrou h, is conducted to and absorbed by saidlocks or masses of metal as rapidly as generated, whereby said conductorWlll not be overheated, and a fireproof insulating material inclosingthe free surface of said conductor.

8. A resistance device for electric circuits, comprising twoblocks ormasses of metal of high specific conductivity, and a conductor of highspecific resistance connecting said blocks or masses of metal, saidconductor being of such small cross-section as to produce the desiredresistance within such a short length thereof, that the heat generatedby the passage of an electric current therethrough will be conducted toand absorbed by the said blocks or masses of metal as rapidly asenerated, whereby said conductor will not ecome overheated, and afireproof insulating material inclosing the free surface of saidconductor.

9. An electrical resistance device, consisting of two blocks of metal ofhi h specific conductivity, and a conductor 0 high specific resistanceand short length connectin said blocks of metal, the free length of Sciconductor being such that the heat generated therein by the passage of acurrent therethrough, is conducted to and absorbed by said blocks ofmetal as rapidly as generated, whereby said conductor will not beoverheated, and means for connecting up 10. An electrical resistancedevice, conl sisting at two blocks of metal of high specificconductivity, and a conductor of high specific resistance and shortlength connecting said blocks of metal, the free length of saidconductor being such that the heat generated therein by the passage of acurrent therethrough, is conducted to and absorbed by said blocks ofmetal as rapidly as generi ated, whereby said conductor will not beoverheated, and a shunt-circiiit leading around said conductor.

11. An electrical resistance device, consisting of a shortconductor ofhigh ecific resistance, connecting two masses or looks of metal of highspecific conductivit the free length of said conductor being suc thatthe heat generated by the passe e of an electric current therethroughwill e absorbed by said blocks of metal as rapidly as generated, wherebysaid conductor will not be overheatedya shunt-circuit leading aroundsaid conductor and means for connecting up said resistance device in anelectric circuit.

12. Anelectrical resistance device, comprising two blocks or masses ofmetal of high specific .conductivity located in close toximit to eachother and a conductor 0 high specific resistance and short length havings of meta its ends embedded into said bloc respectively, thereby leavinga short free length of conductor between said blocks of metal.

13. An electrical resistance device, comrising two massive terminals,com osed of locks of metal of high specific con uctivity located inclose proximity, and a conductorof high specific resistance having itsends embedded into said blocks of metal res actively, to leave a shortfree length of meta between said tcrminals.

14. An electrical resistance device, consisting of two blocks of metalof high specific conductivity and a hi h-resistance conductor connectinsaid bloc s of metal, said conductor being of such short free lengththat the heat generated therein by the passage of a current therethroughis absorbed and dissipated by said blocks of metal as rapidly asgenerate This specification signed and witnessed this 18th day of Ma1906.

ADELl ERT O. BENECKE. Witnesses:

Louis M. SANDERS, FREDK. O. Freeman.

